Differential assemblies are generally known in the automotive industry as devices that supply equal torque to a pair of driving wheels, while allowing each wheel to rotate at different speeds. Generally, differential assemblies have three primary tasks: (1) to direct the engine power to the wheels; (2) to serve as the final gear reduction to slow the rotational rate of the drive shaft before transmitting power to the wheels; and (3) to transmit power to the wheels while also allowing the wheels to rotate at different rates.
In a typical automotive vehicle, a rotating drive shaft engages a ring gear mounted to a differential housing. The drive shaft engages and drives the ring gear to rotate the differential housing. A typical differential housing contains two side gears and several pinion gears. The pinion gears are fixed to the housing by pinion shafts so that the rotating housing drives the pinion gears. The pinion gears drive side gears, each of which is coupled to a corresponding axle shaft of a driven wheel. Thus, the differential is capable of driving a pair of wheels with equal force, while allowing them to rotate at different speeds.
A differential housing is usually integrally formed with a differential carrier. Typically in four-wheel drive applications, for example, the differential carrier and the differential housing are manufactured from a one-piece casting process, which is expensive and requires use of cores and specialized finishing operations.
It is therefore advantageous to develop a lower cost differential assembly and method of manufacturing the same. In addition, it is advantageous to manufacture a multiple piece differential assembly, such as a two-piece differential carrier and a separate differential housing that is less expensive, may accommodate variations, and is simpler to produce. For example, it would be advantageous to have a differential assembly that is capable of accommodating all wheel drive applications as well as different numbers and sizes of pinion shafts and gears.